Steam generating apparatus



May 16, 1933. BROS 1,909,091

STEAM GENERATING APPARATUS Filed Nov. 1931 4 Sheets-Sheet l 40 VENTOF? CHESTER W. BROS 3 2'3 By E! MM ATTO RNEYS Filed Nov. 2, 1931 -4 Sheets-Sheet 2 IN VENTOR CHESTER W BRos r M flue/(MW I ATTORNEY5 May 16, 1933. w BROS 1,909,091

STEAM GENERATING APPARATUS Filed Nov 2, 1931 4 Sheets-Sheet 3 INVENTOR CHESTER W EH05 Eh mm ATTOR BY May 16,1933. w BROS 1,909,091

STEAM GENERATING APPARATUS Filed NOV. 2, 1931 4 Sheets-Sheet 4 CHESTER W. 5905 INVENTOF? 6 MM AT-roRNE-Ys Patented. May 16, 1933 UNITED STATES PATENT OFFICE] 1 CHESTER W. BROS, OF MINNEAPOLIS, MINNESOTA, ASSIGNOR TO WM. BROS BOILER, & MANUFACTURING COMPANY, OF MINNEAPOLIS, MINNESOTA, AT CORPORATION OF MINNESOTA Application filed November 2, 1931-.

This invention relates to new and useful improvements in steam generating apparatus, generally, and more particularly to the furnace of a stationary boiler.

In recent years, considerable advancement has been made in the burning of pulverized fuel, in commercial boilers and large steam generating apparatus, mainly, because of the relatively higher furnace temperatures obtained by the burning of such fuel, and the resultant increase in the boiler rating. Difficulties, however, were experienced when pulverized fuel was first introduced because of the fact that the furnaces of most boilers 'were not designed to withstand the actions of the intense heat resulting from the high furnace temperatures, and also because of the resultant tendency of the burning fuel to form a molten slag which would accumulate on the furnace bottom and walls and eventually tend to destroy them. To prevent this objectionable formation of slag on the furnace walls, it was found that by cooling certain of the walls, this objectionable feature might be substantially eliminated;

In the past it has been common practice to place the furnace. directly under the boiler. To increase the power rating of a given size boiler, a relatively larger furnace is needed, and this is usually accomplished by increasing the height or vertical dimension of the furnace. To thus increase the height of the furnace when the latter is ar ranged under the boiler, naturally results in increasing the overall height of the apparatus, which has been found objectionable in many cases because of insufficient head room in the building in which the apparatus is to be installed. This is particularlytrue in large boilers of the above'type, which often are so high as to make it practically impossible to install such a boiler in a build- 5 ing without first having to change or rebuild STEAM GENE'RATING' APPARATUS Serial No. 572,557.

the roofthereof to accommodate it to the top of the boiler.

It is therefore desirable that a furnace be provided which is so constructed as to be well adapted for the burning of pulverized and other highly combustible fuels, and

whereby the overall height of the boiler and furnace, when set up,-will be considerably less than boiler installations as now commonly set up, thereby providing suchan apparatus having a high rating and, at the,

same time, requiring a low, head room whereby the boiler may be installed in most.

ing them from the actions of the high temper-atures in the combustion chamber; to provide a steam generating apparatus comprising a boiler and furnace situated on substantially the same level whereby the overall height of the apparatus may be greatly decreased, as compared to similar-apparatus now in use; to provide a steam generating apparatus comprising a boiler having cer-.v tain of its tubes arranged within the furnace so as to provide a water cooled bridge wall, and wherein other groups of tubes'are arranged adjacent to the side walls of the furnace and connected with the boiler so that a portion of the water inthe boiler will circulate through sai'd'groups of tubes to thereby cool the side walls of the furnace; to provide a boilerfurnace having groups of water circulating tubes arranged adjacent to the side walls thereof and connected with the main boiler at the rear of the furnace, and

connected at the front of the furnace with suitable upright headers which have their upper ends connected with a horizontally disposed header having a plurality of spaced tubes connecting it with an upper drum of the boiler so as to water cool the ceiling or top wall of the furnace; and, in the general construction and arrangement of the parts of the apparatus whereby a very efficient and compact steam generating apparatus is provided.

Other objects of the invention will appear from the following description and acconr panying drawings and will be pointed out in the annexed claims.

'In the accompanying drawings, there has been disclosed a structure designed to carry out the various objects of the invention, but

it is to be understood that the invention is 1 not confined to the exact features shown as various changes may be made within the scope of the claims which follow.

In the drawings:

' Figure 1 is a vertical sectional view on the line 1-1 of Figure 2, showing my inn proved steam generating apparatus and the relative positions of the boiler and furnace portions thereof, and also the air chamber provided over the furnace;

Figure 2 is a sectional view on the line 22 .of Figure 1, partially in elevation, showing the tubes of the boiler which constitute the water cooled bridge wall at the rear of the combustion chamber, and also showing the air circulating passages at the sides, bottom, and top of the combustion chamber for cooling the walls thereof;

. Figure 3 is a diagrammatic view illustrating how the heated air in the chamber over the furnace may be conducted to the fuel feeding apparatus;

Figure 4 is a vertical sectional view on the line 44 of Figure 5, showing the invention applied to a steam generating apparatus provided with a stoker for supplying it with fuel; and

Figure 5 is a sectional view on the line 5-5 of Figure 4, partially in elevation.

In the selected embodiment of the inven tion here shown, there illustrated in Figure 1, for purposes of disclosure, a conventional boiler comprising upper steam drums 2and 3 and a lower mud drum 4, interconnected by groups of circulatii'ig tubes 5, 6, and 7. These tubes are suitably secured to the drums to provide an integral structure. The boiler is shown mounted within a chamber 8 defined by suitable walls 9 and 1010, a bottom wall or floor 11, and a top wall or roof 12. The ends of the drums 2, 3, and 4 may be suitably supported in the side walls 10 of the structure. Suitable baflies 13, 14, 15, and 16 are shown interposed between certain rows of the tubes of each group of tubes to cause the products of combustion to follow a tortuous path through the chamber 8 to the smoke outlet 17 in the usual manner.

An important feature of this invention re sides in the construction of the furnace and its arrangement with respect to the boiler, whereby the overall height of the apparatus may be reduced to a minimum, and also in the means provided for cooling the furnace Walls.

The combustion chamber 18 of the furnace, as here shown, is defined by opposed side walls 19-19, a bottom wall or floor 21, a top wall or ceiling 22, and a front wall 23. A water cooled bridge wall provides the back wall ofthe combustion chamber and. the particular construction of this wall provides an important feature of the present invention.

The water cooled bridge wall, as best shown in Figure 1, comprises the deflector 16 which is here-shown supported upon a cross-sub-wall 24, dividing the lower part of the chamber 8 from the combustion chamber 18. The front row of tubes of the boiler, indicated by the numeral 25, preferably have their lower portions embedded in the cross wall 24 and extend upwardly therefrom adjacent to the deflector 16 within the combustion chamber, whereby the tubes 25 are subjected to radiant heat of the products of combustion. It will also be noted that the furnace is arranged in substantially horizontal alinement with the boiler whereby the overall height of the apparatus is governed only by the overall height of the boiler unit, irrespective of the furnace. By thus hoii zontally alining the boiler and furnace, the overall height of the apparatus may be reduced to a minimum so that the apparatus may readily be installed in an ordinary building, usually without changing or altering the construction thereof.

The means provided for cooling certain walls of the furnace is clearly shown in Figures 1 and 2, and comprises groups of water circulating tubes 26 arranged adjacent each side Wall 19 and disposed at an incline as shown in Figure 1. The tubes 26 are connected with. the mud drum 4 at the back of the furnace, and at the front of the furnace with a pair of upright headers 27. The upper ends of the headers 27 are connected with a horizontally disposed header 23 by suitable connections 29, as shown in Figure 2, whereby the water circulating through the groups of tubes 26 will flow upwardly,

through the headers 27 and into the horizontally disposed header 28.

A series of water circulating tubes 31 connect the horizontally disposed header 28 with the steam drum 3 whereby the tubes 26 and 31, and headers 27 and 28 are connected in the circulation of the boiler. The tubes 31 are preferably arranged in parallel re" lation to the inclined roof or ceiling 22 of lilii the furnace, and are disposed within the combustion chamber so as to absorb heat from the products of combustion therein. The tubes 31, by reason of their'arrangement adjacent to the ceiling-22 vof the furnace, provide a water screen or cooling means for said ceiling.

The tubes 26 are arranged in close proximity to the inner surfaces of the side walls 19 of the furnace, as shown at the left hand side of Figure 2, and may be suitably supported thereon by suitable hangers or anchors 32 secured in the side walls. Because of the tubes 26 and 31 being angularly disposed as shown,- wat'er from the boiler will freely circulate therethrough whereby these tubes, in addition to cooling the walls of the furnace, also provide means for promoting the generation of steam in the boiler, with a resultant increase in the rating of the boilor withoutrelati'vely increasing the size of the boiler proper. I

Another feature of the invention residesin the means provided for cooling the walls of the furnace in addition to the cooling acti on imparted thereto by the water circulating tubes 26 and 31. As shown in Figures 1 and 2, the sidewalls 19 of the furnace are provided with a plurality of upright air circulating passages 33, These passages at one side of the furnace communicate with the atmosphere at the bottom of the furnace by means of a plurality of ducts 34, and the upper ends of said air passages 33 communicate with an air chamber 35 provided between the ceiling 22 of the furnace and a suitable roof 36. The sides and ends of the chamber 35 are defined by suitable wall portions, as will be noted by reference to the drawings.

The air passages 33 in the opposite wall. of the furnace communicate at their lower ends with a plurality of horizontally disposed air circulating passages 37 arranged beneath the floor of the combustion chamber, and

which horizontal air passages open to the atmosphere by suitable ducts 38 preferably provided beneath the similar ducts 34, shown in Figure 2. I

The air circulating upwardly through the air passages in the side walls absorbs heat from the walls, which is carried upwardly into the chamber 35, as indicated by the arrows in Figure 2. The heated air in the chamber 35 is utilized to facilitate combustion and, in thedrawings, I have shown an air trunk 39 having its upper end connected with the air chamber 35 and its lower end with the usual fuel feeding mechanism 41 provided for feeding pulverized fuel into the combustion chamber 18 through the usual nozzle 40. The fuel feeding mechanism 41 is usually provided with a fan for blowing the pulverized fuel into the combustion chamber, and this fan may also be utilized for drawingthe preheated air from the chamber 35 and injecting it into the combustion chamber, together with the fuel. By thus delivering the preheated air from the chamber 35 into the combustion chamber, combustion of the fuel is greatly facilitated. The fuel feeding mechanism 41 may be of any Well-known type applicable for the purpose, and it is therefore thought unnecessary to show the same in detail.

During operation of the fuel feeding means 41, air is drawn into the air passages in the side and bottom walls of the furnace, as indicated by the arrows in Figure 2, and circulated upwardly into the chamber 35, from whence it is delivered into the combustion chamber by the fuel feeding means, as

hereinbefore described; It will thus be seen that the air thus circulated through the furnace walls, in addition to cooling'said walls, is also used as a means to facilitate combustion.

' Figures 4 and 5 illustrate a boiler and furnace in which the water circulating tubes 26 and 31 arearranged in a manner quite similar to the corresponding tubes shown in Figures 1 and 2, but the air circulating feature has been dispensed. with. The furnace shown is also of the stoker type. In the construction here shown, the front tubes 25 of the group of boiler tubes 7 cooperate with the baflle 16 to provide a water cooled bridge wall similar to theone shownin Figure 1.

\Vhen-the fuelis fed to the furnace by means of a stoker, the water circulating tubes 26 adjacent to the side walls of the furnace are preferably provided with a suitable metal armor 42 commonly known to the trade as side wall chill. The lower portions of the tubes 25 of the water cooled bridge wall are also preferably provided with a similar armor 43 as best shown in Figure 5. The armor 42 and 43 protects the tubes 25 and 26 from the excessive heat of the fuel bed, which usually is supported upon the usual grate 44 of the combustion chamber. The stoker may be of any con-c ventional design and is indicated generally by the numeral 45 in'Figures'4 andv It will also be noted by reference to Figure 5 that the water wall tubes 26 at the sidesof the combustion chamber are preferably embedded in the'brick work of the furnace walls and may be supported therein by suit-' able anchor bolts 46 as shown.-

The novel steam generating apparatus disclosed in this invention has provcn very eflicient and economical in operation. By arranging the combustion chamber along side of the boiler, as shown in Figure l, the

overall height of the apparatus may be reduced to a minimum while, at the same time,

the rating of the boilenmay beincreased without relatively changing the size of the boiler. This results primarily because of the particular arrangement of the furnace withrespect to the boiler whereby it may readily be constructed so as to have ample volume for the products of combustion, and also because of the arrangement of the tubes 26 and 31 within the combustion chamber which, as hereinbefore stated, are subjected to radiant heat of the burning fuel, resulting: in an increase in the production of steam, without relatively increasing the 0perating cost.

By cooling thefurnacc walls as shown in Figures 1 and 2, the furnace is rendered particularly well fitted for burning pulverized fuel, as the danger of slag forming on thewalls thereof is practically eliminated, and the useful operating life of the furnace Walls will also be materially prolonged, resulting in fewer repairs and therefore a lowering of the operating cost. In the drawings, I have shown a boiler of the three horizontal header connected with said upright headers, and an upper group of water circulating tubes arranged ad acent to the upper wall of the furnace within the combustion chamber and connecting said horizontally disposed header with said steam drum, whereby a portion of the water in said boiler will circulate through said upper group of tubes to thereby cool the upper wall of the furnace.

2. In a steam generating apparatus, a

boiler comprising a mud drum and a steam drum interconnected by a series of water circulating tubes, a furnace, a group of water circulating tubes arranged adjacent to each side wall of the furnace and disposed at an incline, the tubes of each of said groups being connected at one endof the fur-'- nace with the mud drum of the boiler and at the opposite end of the furnace with a pair of upright headers, a horizontally disposed header connected between said upright headers, and another group of water circulating tubes arranged adjacent to the upper wall of the furnace within the combustion chamber and connecting said horizontally disposed header with the steam drum of the boiler, whereby a portion of the water in said boiler may circulate through said groups oftubes to thereby cool the walls of the furnace, said upper group of tubes being disposed at an incline opposed to that of the lower groups of tubes.

3. In a steam generating apparatus, a boiler comprising upper and lower drums interconnected by a plurality of water circulating tubes, a furnace substantially horizontally alined with said boiler and comprising a rear wall, certain of the tubes of said boiler cooperating with said rear wall to form a water cooled bridge wall for the combustion chamber of the furnace, groups of tubes arranged adjacent to the side walls of the furnace, and connected at the rear of the furnace with the lower boiler drum and at the front of the furnace with a pair of Vertically disposed headers, said groups of tubes being inclined upwardly from rear to front, and means connecting said upright headers in the circulation of the boiler whereby water will circulate through the tubes of said groups of tubes to cool the side walls of the furnace.

In a steam generating apparatus, a boiler including upper and lower drums intmrconnecterl by a plurality of water circulating tubes, a furnace arranged adjacent to said boiler and substantially horizontally alined therewith and having a rear wall, certain of the tubes of said boiler cooperating with said rear wall to form a water coolcdbridgc wall for the combustion chamber of the furnace, a group of tubes arranged adjacent to each side wall of the furnace, the tubes of each of said. groups of tubes being connected at the rear of the furnace with said lower boiler drum and at the front end of the furnace with a pair of Vertically disposed headers, a, horizontally disbosed header connected between said vertically disposed headers, and a group of spaced apart tubes arranged adjacent to the top wall of the furnace \i ithin the combustion chamber, and connecting said horizontally disposed harder with the upper drum of the boiler whereby a portion of the water 111 said boiler may circulate through said groups of tubes to thereby cool the walls of the furnace, all of the tubes in said groups of tubes being disposed at an incline to facilitate circulation.

5. In a steam generating apparatus, a boiler comprising a mud drum and a steam drum interconnected by a series of water circulating tubes, a furnace, a group of water circulating tubes arranged adjacent to each side w ll of the furnace, the tubes of each of said groups being connected at one end of the 'fllllltlCi-P. with the mud drum of the boiL er and at the opposite end of the furnace with a pair of upright headers, a horiaontah ly disposed header connected between said upright headers, and another group of water circulating tubes arranged adjacent to the upper wall of the furnace within the combustion chamber and connecting said horizontally disposed header with the steam drum of the boiler, whereby a portion of t 5 the water in said boiler. may circulate through said groups of tubes to thereby cool the walls of the furnace, said upper group of trgies being substantially horizontally dis- )ose I In Witness whereof, I have hereunto set my hand this 30th day of October 1931.

' CHESTER W. BROS. 

